1. Field of the Invention
The present invention relates to a pump and, in particular, to a pump that has adjustable pumping pressures.
2. Description of the Related Art
Air pumps which have high volume and high pressure setting modes are known. In using the pump, the user usually selects the high volume mode until either the desired pressure is reached or the effort becomes too high for that particular person. Then, the user switches the setting to low volume which causes the effort to decrease dramatically, and the user can continue to pump to the desired pressure.
Taiwan Patent Publication No. 524274 discloses a pump that has selectable high volume and high pressure settings. The pump includes an outer, a middle and an inner tubes 30, 40, 50 coaxially disposed for air flowing therethrough. When in the high volume setting, the outer and inner tubes 30, 50 are opened to the pump head. When in the high pressure mode, a switching device 20 mounted adjacent to a foot pedal blocks the outer tube 30 from permitting airflow to the pump head, thus resulting in only the inner tube 50 being opened to the pump head. Unfortunately, while the user can keep one foot on the pedal and switch the settings with another foot, it is very likely that the user loses his or her balance during manipulation of the switching device. Furthermore, the switching device is easy susceptible to mis-actuation by the user's foot.
The present invention is, therefore, intended to obviate or at least alleviate the problems encountered in the prior art.